org.apache.spark.util.kvstore

Class LevelDB

Object

org.apache.spark.util.kvstore.LevelDB

All Implemented Interfaces:

java.io.Closeable, AutoCloseable, KVStore

public class LevelDB
extends Object
implements KVStore

Implementation of KVStore that uses LevelDB as the underlying data store.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	LevelDB.TypeAliases Needs to be public for Jackson.

Constructor Summary

Constructors

Constructor and Description
LevelDB(java.io.File path)
LevelDB(java.io.File path, KVStoreSerializer serializer)

Method Summary

Modifier and Type	Method and Description
void	close()
long	count(Class<?> type) Returns the number of items of the given type currently in the store.
long	count(Class<?> type, String index, Object indexedValue) Returns the number of items of the given type which match the given indexed value.
void	delete(Class<?> type, Object naturalKey) Removes an object and all data related to it, like index entries, from the store.
<T> T	getMetadata(Class<T> klass) Returns app-specific metadata from the store, or null if it's not currently set.
<T> T	read(Class<T> klass, Object naturalKey) Read a specific instance of an object.
void	setMetadata(Object value) Writes the given value in the store metadata key.
<T> KVStoreView<T>	view(Class<T> type) Returns a configurable view for iterating over entities of the given type.
void	write(Object value) Writes the given object to the store, including indexed fields.

Methods inherited from class Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LevelDB

public LevelDB(java.io.File path)
        throws Exception

Throws:

Exception

LevelDB

public LevelDB(java.io.File path,
               KVStoreSerializer serializer)
        throws Exception

Throws:

Exception

Method Detail

getMetadata

public <T> T getMetadata(Class<T> klass)
                  throws Exception

Description copied from interface: KVStore

Returns app-specific metadata from the store, or null if it's not currently set.

The metadata type is application-specific. This is a convenience method so that applications don't need to define their own keys for this information.

Specified by:

getMetadata in interface KVStore

Throws:

Exception

setMetadata

public void setMetadata(Object value)
                 throws Exception

Description copied from interface: KVStore

Writes the given value in the store metadata key.

Specified by:

setMetadata in interface KVStore

Throws:

Exception

read

public <T> T read(Class<T> klass,
                  Object naturalKey)
           throws Exception

Description copied from interface: KVStore

Read a specific instance of an object.

Specified by:

read in interface KVStore

naturalKey - The object's "natural key", which uniquely identifies it. Null keys are not allowed.

Throws:

java.util.NoSuchElementException - If an element with the given key does not exist.

Exception

write

public void write(Object value)
           throws Exception

Description copied from interface: KVStore

Writes the given object to the store, including indexed fields. Indices are updated based on the annotated fields of the object's class.

Writes may be slower when the object already exists in the store, since it will involve updating existing indices.

Specified by:

write in interface KVStore

Parameters:

value - The object to write.

Throws:

Exception

delete

public void delete(Class<?> type,
                   Object naturalKey)
            throws Exception

Description copied from interface: KVStore

Removes an object and all data related to it, like index entries, from the store.

Specified by:

delete in interface KVStore

Parameters:

type - The object's type.

naturalKey - The object's "natural key", which uniquely identifies it. Null keys are not allowed.

Throws:

java.util.NoSuchElementException - If an element with the given key does not exist.

Exception

view

public <T> KVStoreView<T> view(Class<T> type)
                        throws Exception

Description copied from interface: KVStore

Returns a configurable view for iterating over entities of the given type.

Specified by:

view in interface KVStore

Throws:

Exception

count

public long count(Class<?> type)
           throws Exception

Description copied from interface: KVStore

Returns the number of items of the given type currently in the store.

Specified by:

count in interface KVStore

Throws:

Exception

count

public long count(Class<?> type,
                  String index,
                  Object indexedValue)
           throws Exception

Description copied from interface: KVStore

Returns the number of items of the given type which match the given indexed value.

Specified by:

count in interface KVStore

Throws:

Exception

close

public void close()
           throws java.io.IOException

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface AutoCloseable

Throws:

java.io.IOException